Polymerization of ethylene to normal alpha olefins with a trialkylaluminum catalyst in a tubular reactor



Dec. 2, 1969 FERNALD ETAL 3,482,009

POLYMERIZATION OF ETHYLENE TO NORMAL ALPHA OLEFINS WITH A TRIALKYLALUMINUM CATALYST IN A TUBULAR REACTOR Filed Jan. 9, 1967 2 Sheets-Sheet 1 Q Q Q Q a g 2 a A 2 N/J.-770- u JAG) 890 70/1 Dec. 2, 1969 FERNALD ET AL 3,482,000

POLYMERIZATION OF ETHYLENE To NORMAL ALPHA OLEFINS WITH A TRIALKYLALUMINUM CATALYST IN A TUBULAR REACTOR Filed Jan. 9, 1967 2 Sheets-Sheet z United States Patent 3,482,000 POLYMERIZATION OF ETHYLENE TO NORMAL ALPHA OLEFINS WITH A TRIALKYLALUMIN UM CATALYST IN A TUBULAR REACTOR Herbert B. Fernald, Glenshaw, Pa., Bernard H. Gwynn,

3,482,000 Patented Dec. 2, 1969 formations of olefins other than n-rz-olefins to n-u-olefins, in mols, at any particular point in the system is proportional to the weight ratio of product (C and higher olefins) to unreacted ethylene at such point. This can be seen from the following example.

Leawood, Kans., and Alfred N. Kresge, Verona, Pa., 5 assignors to Gulf Research & Development Company, EXAMPLE I Pittsburgh, Pa., a corporation of Delaware C ti fi .j t f application s 153, 15 Into an autoclave having a volume of 860 m1ll1l1ters Nov. 21, 1961. This application Jan. 9, 1967, Ser. equipped with a stirrer to maintain the contents thereof No. 608,127 10 in a substantially homogeneous state, and which was main- Int. Cl. C07c 3/10 tained at a temperature of 200 C. and a pressure of 4000 260683- 7 Claims pounds per square inch gauge, there was introduced continuously over a period of 10.25 hours 31.0 grams per minute of a mixture comprising 94.35 percent by weight ABSTRACT OF THE DISCLOSURE 15 of ethylene, 4.45 percent by weight of heptane solvent A process for the polymerization of ethylene to normal and 1.20 percent by weight of triethylaluminum. There and branched a-olefins in the presence of an organo was continuously removed from the autoclave 31.0 grams metallic catalyst. An unexpectedly high selectivity towards per minute of product. The product was discharged connormal a-olefins is achieved by performing the reaction tinuously to a gas-liquid separator maintained at 130 F. in a tubular reaction zone wherein the amount of polymer 0 and a mospheric pressure. The eifiuent gases were measincreases throughout the length of he reactor tube. The ured and analyzed. The liquid reaction product was then reaction temperature is between about 180 and 240 C., subjected to hydrolysis, in order to destroy the catalyst, there is between bout 1 10- nd 1 10 mol of with 10 percent by weight of a percent aqueous solucatalyst per mol of ethylene, and the polymerization tion of sulfuric acid. The organic layer was washed with proceeds until there is a conversion of at least about 25 an equal volume of water and dried with anhydrous calpercent of said ethylene to polymer product. cium sulphate. Similar runs were made at different ratios of total polymer to unreacted ethylene. The data obtained are set forth below in Table I.

TABLE I RunNo 1 2 3 4 5 6 7 g V/ F or (Volume of Reactor in Milliliters)! Total Feed in Grams Per Hour) 0.558 0. 549 0.507 0.585 0.617 0.672 0.724 Percent by Weight of Oatalystin Feed.. .0 1.57 1. 41 1.44. 1.62 1. 73 1.80 1.96 Percent by Weight of Solvent in Feed... 4.45 5.83 5. 22 5. 34 6.00 6.55 6.65 7.29 Percent by Weight of Ethylenein Feed 94.35 92.60 93.37 93. 22 92.38 91.82 91.55 90.75 Percent by Weight of Ethylene Converted 30.4 55.5 56.4 57.5 75.6 80,1 86.1 91.0 Mols of n-oe-olefin Polymer in Product/ Total Mols of Olefin Polymerin Product 84.1 82.2 80.4 82.2 74.9 75.6 68,4 59,8 B or (Mols of Internal and Branched Chain Terminal Olefin)/ (Mols of n-N-olefin Polyemr) .189 0.216 0.244 0.216 0.336 0.323 0.462 0. 673 P/E or (Weight of Total Polymer in Product)! (Weight of Ethylene in Product) 0.436 1. 248 1.292 1.353 a. 100 4.02 e, 19 10.11

This application is a continuation-in-part of Ser. No. 153,815, filed Nov. 21, 1961, now abandoned.

This invention relates to a process for the polymerization of ethylene and more particularly to a process for the polymerization of ethylene to obtain a product predominating in cc-OlCfinS.

Ethylene can be polymerized at elevated temperatures in the presence of an organo metallo compound to obtain a product containing olefins having from four to twenty and even higher number of carbon atoms. The olefin product so produced includes straight and branched internal olefins and straight and branched terminal or aolefins. The latter olefins are extremely attractive for use in many chemical reactions, for example in reactions with aromatics ultimately to produce synthetic detergents. It would be extremely desirable, therefore, to operate such process so that a maximum amount of a-olefins are produced and little or no straight and/or branched internal olefins are obtained.

We have found that ethylene can be polymerized at elevated temperatures in the presence of an organo metallo compound to obtain a product predominating in a-olefins by the relatively simple expedient of carrying out the reaction continuously in a plurality of stages, preferably in an infinite number of stages, wherein the amount of polymer relative to said ethylene is different in each of said stages.

We have discovered in the above-defined reaction, regardless of the type of system in which the same is carried out, that the ratio R, or the instantaneous rate of The data so obtained are graphically represented in FIGURE I wherein the ratio R (mols of internal and branched chain terminal olefins to mols of N-DL- OICfiIIS) is plotted against the weight ratio of total polymer in the product to ethylene, P/E. FIGURE II is a graphical representation of data obtained from FIGURE I wherein the mol percent of n-rx-olefin in the polymer product is plotted against the previously-defined ratio R.

In a continuous stirred autoclave, that is, wherein over the course of the reaction the weight of the material entering the autoclave is equal or about equal to the weight of material leaving the autoclave and substantially complete mixing is obtained, other conditions being about the same, the composition of the contents of the autoclave and the material leaving or product obtained is substantially constant with time. Therefore, the average composition of the product obtained in a continuous stirred autoclave is substantially equal to the instantaneous composition of the contents of the reactor, and the weight ratio, P/E, of polymer in the product at any point in the contents of the autoclave to the unreacted ethylene can be represented by the following equation:

wherein x represents the fractional conversion of ethylene to C., polymers and higher.

The significant difference in the n-or-olefin content of the product obtained in the polymerization process described herein whenthe same is carried out in a coil or Mol Percent n-a-olefin in Polymer Product Stage 4 Mol Percent n-a Stage 3 percent of the ethylene was converted to polymer. The data for the coil reaction was obtained from FIGURE III, which will be discussed hereinafter. The data in Table II show that the amount of n-a-olefin in the product is always greater when the polymerization reaction is carried 5 out in a coil reactor rather than in a single continuous stirred autoclave or series of stirred autoclaves for the same total conversion of ethylene to polymer. Equal conversion per stage was used for convenience of calculation. Other combinations will give somewhat different :0,605 the results, but in no case will a finite number of autoclaves in series yield results better than a coil reactor for the same level of ethylene conversion. In Table II x and R are as defined hereinabove, and n-a-refers to n-a-olefins.

TABLE II StageZ Mol M01 Per- Percent cent n-a R n-a Stage 1 From FIGURE I it can be seen that when P/E=9,

f continuous stirred autoclaves rather than in a single continuous stirred autoclave is illustrated by the following, employing therefor the equation derived Number of Stages even in a series 0 above and data in FIGURES I and II. In a continuous stirred autoclave wherein a conversion of 90 percent of ethylene to polymer is obtained =0.605. According to FIGURE II, when R Where the process is carried out in two continuous stirred percent n-wolefin in the product amounts to 62.4 percent.

autoclaves to obtain a conversion of 90 percent of the Type of Reactor Coil Stirred Flow Autoclave..-

From the above it is apparent that for the same amount of ethylene converted to polymer the largest amount of n-a-olefins is obtained in a coil reactor. In a single tained in a coil reactor. Even the use of two continuous stirred autoclaves in series resulted in a significant increase in the amount of n-a-olefin produced, and this increase is maintained and enlarged by the further use of more com That the amount of n-a-olefin in the product is always greater when the polymerization reaction is carried out EXAMPLE II Into one end of a stainless steel coil having a length of 101.5 feet and an internal diameter of 0.25 inch there a-oletln Content Polymer, Percent Mol Percent Ethylene Solvent V/F Converted RCH=CH1 RC2=CH and the same amount of reaction x in the first stage is equal to 0.45, he first 30 continuous stirred autoclave the amount of n-a-olefin obtained was reduced appreciably over the amount obtinuous stirred autoclaves in series.

=0.204 for the in a coil reactor rather than in a single continuous stirred fthe Olefin autoclave at equal conversion of ethylene to olymer is P polymers formed in the first stage 1s n-a-olefin, but only further seen from the following f the olefin polymers formed in the olefin. Since equal amounts of reacthe effluent from the second stage will be the average of the two or 72.8 mol percent was continuously introduced 26.8 grams per minute at 4000 pounds per square inch gauge and 200 C. of a mixture comprising 86.50 percent by weight of ethylene, herein 90. 12.05 percent by weight of heptane solvent and 1.45 per- TABLE 111 Inside Tempera- Feed Composition, Wt. Percent Length, Diameter, ture, Pressure,

Inches C. p.s.i.g. Ethylene Catalyst lnfinite.

ethylene to polymer, takes places in each,

ge and 0.605 for the second stage. From FIG- olefin. Similarly, three, four or more stages can be calculated.

The data obtained above have been tabulated below in Table II. For purposes of comparison, Table II also Tubular Reactor Feet in the second stage to 0.9. Therefore P/E in t stage is equal to and in the second stage to According to FIGURE I in such case R first sta URE II it can be seen that 83.1 mol percent 0 62.4 mol percent 0 second stage is n-ation occur in each stage Il-occontains data obtained using a coil reactor w 00000000530050440703015130 llLllnmamnmLlfiqwemqwfilfiaoml 5 7 3 8 0 36922 5698 6 6 1 2 mmm4 4 910 4357m1%M3M5HQ1Mm w l1LlQLLlLLLlLLLLLZZLLL M mmmmmmmmmmmmmmmmmmmmmmmmmmmmm cent by weight of triethyl aluminum. 26.8 grams of product was continuously removed at the exit end of the coil. The product removed from the coil was treated as in Example I and analyzed for its u-olefin content. The data as well as the u-olefin content of this run are listed From the above it is apparent that best results are obtained by carrying out the reaction described herein in an infinite number of stages, and that for purposes of this invention such system is best exemplified by a tubular reactor which is a reactor having an elongated reaction in preceding Table III as Run No. 20. The data from addi- 5 zone. A tubular reactor as herein employed can be said to tional runs made in tubular reactors at various reaction possess an infinite number of stages, because each increconditions are also set forth in Table III. In Runs Nos. 9 to ment thereof is separate and distinct in its composition 31 triethyl aluminum was employed as catalyst, While from any and all other increments which can be said to in Runs Nos. 32 to 37 triisobutyl aluminum was the cat- 10 form a part thereof. The elongated reaction zone is defined alyst. In all of the runs except Runs Nos. 36 and 37 the as one wherein little or no back mixing of the contents solvent employed was n-heptane. In Run No. 36 the solthereof occurs and wherein the elongation factor (ratio of vent consisted of 49.3 percent by weight of n-hexene-l length to inner diameter) is generally in excess of about and 50.7 percent by weight of butene-l, while in Run No. five. A single continuous stirred autoclave has been shown 37 the solvent was n-hexene-l. V/F in the table has the to be ineffective for purposes of this invention, while a same meaning assigned to it in Table I. The rx-olefin conplurality of such autoclaves, which can theoretically ap tent is given in terms of straight chain and branched chain proach the system in a coil, can be elfective. Another systerminal olefins. tern which can exist is a continuous autoclave similar to The data of Tables I and II are graphically illustrated the one described above but which is not intentionally in FIGURE III wherein the mol percent of n-u-Olefin in Stirred. In the event only a small amount of stirring octhe product is plotted against x, which is the fractional l rs therein as a result of mixing or otherwise, it is seen conversion of ethylene to C polymers and higher. It can h t a plurality of separate and distinct stages are presbe seen that for the same amount of ethylene converted ent therein, a d t r re such system is comprehended to 1 h amount f -el fi i th l mer for use in carrying out the process of this invention. Should product obtained in the coil is always greater than the th am unt of mixing be increased and somewhat apttmount f 1 fi i th polymer product bt i d in proach the system of a continuous stirred autoclave wherethe single stirred flow autoclave. Moreover, FIGURE III in the miXtllre therein approaches homogeneity, it is pshows that at fractional conversions of ethylene in the Parent that the Same iS n uita le f r use in the pracrange from above 0 to percent, the improvement of a tiee f t s inv nti n. coil reactor of this invention over a stirred autoclave is 30 I11 VieW 0f the feet that the Production of nis comparatively smaller and more constant than in higher the Object of the PiecesS defined herein, ethylene is the fractional conversion ranges. In this very low fractional Sole Olefin Which can be p y in the chaige- The P conversion range, especially where there is a negligible e Obtained, as noted, Wiii predominate in n- 01efins and quantity f product, the improvement i h 11 reactor w1ll constitute generally at least about 7'0 molar percent is probably due merely to efficiencies inherent in continuthereof, Preferably at least about 85 molar Percenh The ous over batch operation. In contrast, FIGURE III shows h-e'oieiihs Pmdueed W111 a fr m four to 40 or more that at fractional conversions above about 30, 40 or 50 carbon atomspercent the improvement due to the effect of this in- The Ctiteiyst p y can he defined y the following vention starts to become manifest. The improvement of Structural formula: 'a b e d, in M is a metal the coil reactor over the stirred autoclave increases stead- 40 Selected i the alkali Or a kaline earth metals and a ily from these intermediate fractional conversion levels can he e p Or 1s a metal selected from the until nearly complete ethylene conversion is reached. giouh Consisting of ahtmlmlm, gallium, ihdimllm and However, FIGURE 111 shows that it is desirable to avoid beryllium n b can be e t one or R is lected a fractional conversion of ethylene greater than about 85 e t gro p consisting of monoval t saturated or 90 percent because at these very high conversion levels aliphatic or 2Lheyeiie iatileals, mohovalent aromatic radia drop of the n-a-olefin content even in a coil reactor Cells of y Combination thereof; X is lected from the effiuent begins to occur. group consisting of hydrogen and halogen. The sum of 0 Residence times in accordance with this invention will and d is equal to the total valences represented by the generally be at least about 5 minutes, preferably at least metals, and when X is a halogen 0 must be at least one. about 10 minutes, and most preferably at least about 20 Exa l of catalysts which can be employed include to 30 minutes.

Not only must the reaction defined herein be carried Be(C2H5)2 L1C2H5= AlHe, HAKCHQZ a z s out continuously in a plurality of stagesl, plrefelrlably in an A1( A1(C2H5)3, A1(C4H9)3, A1(C3H7)3 infinite number of stages, but it is critica t at t e pressure of the reaction be maintained at all times in excess of at Al(C6H5)3 Ga CH3i3i Ga(C2H5)3i 2 5 3 3)a 133st atbput t10120 per square inch rgaauge},1 pgraegr- B (C H Na(c5Hu) 1 c1 A1(C2H5)C12 a a eas a on oun s er squa 1n e.

Thi is shown below in Table IV. In all of its aspects this AuctHehecll-et AMQIHQZCI, L1A1H4, 4 table is similar to Table III. The solvent employed Was n- Li 1 H NaAl(C -H Mg(AlH )2, z 5)z, heptane. In each of Runs Nos. 40, 41, 42, 43 and 44 the catalyst was triethyl aluminum, while in Runs Nos. 38, The cataiyst can be used as Such: but pieiei'flhiy 15 3'9, 45 and 46 the catalyst was triisobutyl aluminum. Pioyed With about about 99 Percent y Welght th r The data f o Table IV are l hi ll i l d of an inert hydrocarbon solvent such as saturated aliphatics i FIGURE 11L (n-pentane, isopentane, hexane, n-heptane, isooctane, 11-

TABLE IV Tubular Reactor zx-olefin Content of Polymer,

Inside Tempera- Feed Composition, Wt. Percent Percent M01 Percent Run Length, Diameter, ture, Pressure, Ethylene No. Feet Inches C. p.s.i. g. Ethylene Catalyst Solvent V/F Converted ROH= CH R 0 (311,

dodecane, merusol oil, paraffinic oils, kerosene, etc.), alicyclics such as cyclohexane, cyclopentane, etc., aromatics such as benzene, toluene, etc. Initiators, activators or inhibitors (other than the catalyst defined above) are not needed in the presence defined, and yet a polymer product having a high u-olefin content over the entire range of polymer obtained is assured. The amount of catalyst required herein is not critical and can be from about 1 10 to about 1x10" mols thereof per mol of ethylene. These ratios permit repeated alkyl growth and splitting cycles at each molecule of catalyst to produce a great many mols of a-olefin per mol of catalyst.

The temperature of the reaction is between about 180 and 220 or 240 C. Temperatures below this range tend to favor only the growth of alkyl groups on the catalyst, temperatures above this range tend to flavor only the splitting of alkyl groups from a growth product, while temperatures within this range favor both growth and splitting reactions. The upper range of pressure employed is not critical and can be as high as about 1000 atmospheres or even higher, but the lower perssure range, however, is critical. In order to assure reaction of ethylene at all times and to avoid the reaction of polymer, it is critical in the process of this invention that the pressure in the reactor be at all times sufliciently high to maintain the ethylene and the contents of the reactor substanially in a single phase. By single phase we mean to refer to a system wherein all of the components thereof are substantially of the same state of existence and are homogeneously distributed throughout said system. Thus the pressure in the reactor must at all times be at least about 1000,

preferably at least about 2000 pounds per square inch gauge. The great advantage of employing a multiple number of stages, particularly a coil or tubular reactor, in the process of this invention resides in the fact that once having selected a reaction pressure to maintain a single phase operation, the same is maintained throughout the course of the reaction, and there is no danger that as the ethylene is polymerized a pressure reduction will ensue and a two phase system, with its attendant disadvantages, will exist.

As soon as it is desired to terminate the reaction, the product obtained is treated in any suitable manner to deactivate the catalyst and the desired portions of the gross product are recovered. Thus, the gross product is reduced to atmospheric temperature and atmospheric pressure, upon which the gaseous olefins are flashed off. The catalyst is deactivated, for example, by contact with sufiicient acid, base, water or alcohol to react stoichiometrically with the catalyst. For example when an acid or base is employed an aqueous layer is formed, which is then separated from the organic layer, and the remainder, including the solvent, can be separated into its component parts by distillation. If desired the catalyst can be deactivated by contact with oxygen or halogens or any other material which reacts with and suitably destroys the catalytic activity of organo metallo compounds.

Obviously, many modifications and variations of the invention as hereinabove set forth, can be made without departing from the spirit and scope thereof, and therefor only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for polymerizing ethylene to obtain a product predominating in normal alpha olefins having from four to 40 carbon atoms which comprises continuously subjecting ethylene to polymerization conditions at a temperature of about 180 to about 240 C. in the presence of trialkylamluminum as substantially the sole catalyst, said catalyst being present in an amount from about 1 X 10- to about 1 X 10* mols per mol of ethylene, in a tubular reaction zone wherein the pressure is at least about 1500 pounds per square inch gauge throughout the tubular reaction zone and the amount of polymer increases throughout the length of said tubular reaction zone, and the residence time being sulficient to polymerize at least about 30 percent of said ethylene to polymer.

2. The process of claim 1 wherein at least about 40 percent of said ethylene is polymerized to polymer product and the residence time is at least about 5 minutes.

3. The process of claim 1 wherein between about 50 and percent of said ethylene is polymerized to polymer product and the residence time is at least about 5 minutes.

4. A process for polymerizing ethylene to obtain a product predominating in normal alpha olefins having from four to 40 carbon atoms which comprises continuously subjecting ethylene to polymerization conditions at a temperature of about to about 240 F. in the presence of trialkylaluminum as substantially the sole catalyst, said catalyst being present in an amount from about 1 X 10- to about 1 x 10' mols per mol of ethylene, in a tubular reaction zone wherein the pressure is at least about 2000 pounds per square inch gauge throughout the tubular reaction zone and the amount of polymer increases throughout the length of said tubular reaction zone, and polymerizing at least about 40 percent of said ethylene to polymer with a residence time of at least about 5 minutes.

5. A process for polymerizing ethylene to obtain a product predominating in normal alpha olefins having from four to 40 carbon atoms which comprises continuously subjecting ethylene to polymerization conditions at a temperature of about 180 to about 220 C. in the presence of trialkylaluminum as substantially the sole catalyst, said catalyst present in an amount from about 1 X 10* to about l X 10" mols per mol of ethylene, in a tubular reaction zone wherein the pressure is at least about 2000 pounds per square inch gauge throughout the tubular reaction zone and the amount of polymer increases throughout the length of said tubular reaction zone, and polymerizing at least about 30 percent of said ethylene to polymer with a residence time of at least about 5 minutes.

6. A process for polymerizing ethylene to obtain a product predominating in normal alpha olefins having four to 40 carbon atoms which comprises continuously subjecting ethylene to polymerization conditions at a temperature of about 180 to about 240 C. in the presence of trialkyl aluminum as substantially the sole catalyst, said trialkyl aluminum being present in an amount from about 1 X 10- to about 1 X 10- mols per mol of ethylene, in a tubular reaction zone wherein the pressure is at least about 1500 pounds per square inch gauge throughout the tubular reaction zone and the amount of polymer increases throughout the length of said tubular reaction zone, and polymerizing at least about 30 percent of said ethylene to polymer with a residence time of at least 5 minutes.

7. The process of claim 6 wherein said trialkyl aluminum is triethyl aluminum.

No references cited.

PAUL M. COUGHLAN, 111., Primary Examiner mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,482,000 Dated December 2, 1969 Patent No.

Inventor(s) Herbert B. Fernald, Bernard H. Gwynn and Alfred N. F

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In TABLE I, Run No. 1, second line, 12.0" should read --l.20-.

In TABLE I, Run No. 6, third line, "6. 55" should read -6.45-

In TABLE I, three lines from bottom, n-N-olefin" should read -n-oL-olefin-.

In TABLE III, last column, "RC =CH" should read R C CH Column 5, line 19, "II" should read --III.

Column 6, line 42, "indimum" should read -indium-.

SIGNED AND SEALED AUG 4 -1970 (SEAL) Attcst:

Ed d M. Fletcher, Ir WILLIAM E- BGIH'UYIIEB, JR- Atmafing Officer I Gomissioner of Patents 

